The Fit Brain

You love the runner’s high, chiseled physique, steady energy, knock-out sleep, and that alluring post-workout glow. And, sure, there’s always the extraordinary cardiovascular benefit, cancer deterrent, anti-inflammatory impact, and age reversal effect. If that isn’t enough congratulations for your fitness endeavors, here’s more. Physical activity helps fortify your brain as well as your muscles. Yes, exercise goes to your head in dramatically healthy ways – throughout the course of a lifetime. Let’s examine.

Changing the Brain

Exercise supports the brain in a number of ways. Most obviously, exercise increases blood flow to the brain, which provides more oxygen and energy but also reduces free radical damage and enhances memory. Researchers also know that exercise stimulates the creation of new neurons and the production of brain-derived neurotrophic factor (BDNF), a chemical that is instrumental in neuron preservation and formation. And then there’s the impact on gene expression (always a favorite of mine). Exercise specifically promotes gene expression that supports plasticity, the brain’s crucial power to alter neural pathways.

A more recent study highlights exercise’s role in boosting the brain’s stem cell activity – essentially the ability to divide and differentiate throughout our lifetime. Research at Northwestern University’s Feinberg School of Medicine shows that exercise moderates the activity of bone-morphogenetic protein (BMP), which reduces stem cell responsiveness in the brain. Within a weeks’ time, BMP levels were halved in lab mice that ran on a wheel, and an opposing protein called Noggin increased. As a result, the mice displayed remarkable adeptness in cognitive tests.

In addition to enhancing cognitive performance and stimulating ongoing brain growth, exercise also influences the chemical balance related to mood. Research has long connected physical activity with relief of depression and anxiety. Exercise not only stimulates the brain’s release of “feel good chemicals” like endorphins that induce calm and contentment but also supports the brain’s efficient use of dopamine by increasing the number of receptors and the time dopamine remains in the synapses (PDF).

When it comes to the “aging brain,” exercise rewrites the script on that notion. Physical activity can not only preserve brain function but can turn back the clock. As mentioned, exercise keeps the brain’s stem cells working efficiently over the course of a lifetime and preserve brain tissue density. The difference shows. When researchers scanned the brains of fifty-five subjects (ages 55-79), those with the fittest profile (as measured by their maximal oxygen uptake) showed significant differences in the frontal, temporal, and parietal regions of the brain, areas related to learning and memory functions.

Researchers have also found that sustained exercise improves cognitive measures in older adults already experiencing mild memory loss.

Which Exercise?

So, what kind of exercise and how much are we talking here? Science is currently chasing that one down. A Taiwanese study compared mice that played on wheel at their own pace versus mice that were provoked to run at fast speeds. Although researchers found changes in the brains of both groups, the mice that got the more intense workout sported more numerous and more cognitively complex alterations. Their conclusion? Different exercise elicits different changes. Other research, however, suggests that more intense cardiovascular activity spurs more dramatic improvements in cognition and memory. And let’s not leave out resistance training. A recent Canadian study found that resistance training improved executive functioning measures related to attention and conflict resolution. Moderate levels of exercise appear to be effective, but any level – and amount – of activity leaves a positive impact.


The evidence clearly shows, however, that exercise sharpens our mental acuity at any point in our lives. In children, of course, there are plenty of cognitive and behavioral benefits. Study after study (PDF) has demonstrated that physical activity boosts academic performance as well as cognitive related functioning itself in areas such as attention, planning, and organization. (Was there ever any question on that one?)

Most research, however, has focused on older adults who have either been active throughout their lives and those who take up exercise in their later years. The fact is, the more sustained exercise is over a lifetime, the better. Research suggests that a “cognitive reserve” exists in those who were active early in life. Every workout adds to the overall – and lasting – benefit. Finally, experts believe that the best impact comes from a potent synergy between exercise and good nutrition. Now where have I heard that one before?

Have a great day, everyone, and be sure to share your thoughts!

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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33 thoughts on “The Fit Brain”

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  1. In the book “American Idle” the author shares some research indicating that when exercise is forced it does not impart the same cognitive benefits as when the exercise is voluntary or playful.

  2. I do neuroscience research and am convinced that brain health is one of the areas where “chronic cardio” is actually OK.

    I understand the dissuasion against chronic cardio in terms of fat loss, but I think it has immense benefits for brain health.

    I myself don’t feel right unless I get in immense amounts of cardio exercise each week. I felt it was the only real solution to serious mental problems I faced (severe depression, mild-PTSD) — (and continue to face, but I’m seeing slow, gradual improvement; probably never back to baseline, though).

    1. JM- Would you say that cardio is necessary for optimal brain health in general, or only as it relates to depression?

    2. But does it have to be at the chronic level? I go for one or two walks per day, usually along the river. Part of the time I pump it up, but mostly it’s just staying active and taking in the vibes of being in nature. Brisk but not “cardio.” Very important for my mental health.

    3. what is immense amount for you? frequency? length of workout? heart rate?

    4. I also do cognitive neuroscience research. Do you have any suggestions for papers related to this issue?

    1. I came across Spark People about 1-2 months ago – very interesting. I never got the book and kind of let it all go since I knew I loved being primal.

      What do you think about the book overall? Does it have similar principles to the primal lifestyle? I am just wondering if it would be a good read or not.

      1. “Spark” Is a very interesting book, I would definatley recommmend it. As far as if it has principle similar to primal or not. I would yes and no. It does not focus on overall lifestyle change, diet etc.

        It is written by a practicing pyschiatrist who also does research. He focuses mainly on aerobic exercise, but shows how it improve cognitive ability, memory, add, adhd, alzheimers, depression etc. He talks about how he has used it with his patients, as well as going into the neurochemistry, hormones etc.

        He differs from Primal as far being an advocate for chronic cardio, but its not the obnoxious conventional wisdom style. Then again I read the book before I knew anything about the primal lifestyle.

  3. I have just been researching pubmed on a similar line and maybe MDA has already addressed the issue of motor learning and neural adaptation versus muscle hypertrophy in the role of building strength and muscle mass.
    I recently wrote a short article on Bodyweight exercises suggesting that the first objective in doing them is to learn how to do them.
    My objective was to suggest that “getting bigger or stronger” should come secondary and as a result of the primary objective of learning how to control your body through exercise.
    Would love to get your extended take Mark in an awesome blog post.

    1. Besides learning to control your body, having fun should be a goal too. In Stuart Brown’s ‘Play’, he discusses the benefits of physical play on mood disorders.

      Dancing, I think, is one hefty combination of exercise of the body and mind, while combining the benefits of play and creativity… I’d like to see Mark’s take on dancing.

  4. Hm, not really about this article as much as some comments I’ve seen here, all mood-“disorders” arent only due to food/fitness, should really link some of these people to some spiritual material (Like Eckhart Tolle for example) I don’t think the emotional maturity in general is very high.

    Gonna type you a mail with subconscious beliefs that can cause tremendous amounts of stress and how you in many times can solve it by just understanding the situation at hand, thanks for a great site.

    1. Sounds interesting – any chance of a copy? Or maybe Mark can do a blug post…

  5. What about mental exercise, as opposed to physical, for the maintenance of a fit brain?

    Crosswords, chess, debate, thinking. One would think those exercises would help maintain a fit brain, as opposed to say, squats?

    Or did I miss the point as usual?

    1. Of course mental workouts like chess, crossword puzzles will help keep your mind sharp but physical fitness is another way to enhance your mental capabilities, quick thinking, etc.

  6. Great article. I have noticed throughout the years that I have been more on “my game” when I workout consistently. In the Army they preach fitness (you’d be amazed at how many fat and out of shape people are in) and I truly believe this to be the main reason. Yes running, bodyweight lifts will ultimate make you stronger, more agile but it makes the brain that much sharper when things get hectic. The ability to keep a cool head in tough situations is always important and now I have a better understanding of why that is.

  7. Way back a million years ago when I was teaching physical education, it was my observation that generally, the best students were also the best athletes. Not always true but mostly true.

    1. Mm, I found that too but that may just be that these individuals apply themselves well to all areas of their life and hence become good students and good athletes.

    2. Nothing put me off exercise for years more than middle school and high school phys ed classes. At some point I learned physical activity didn’t have to be painful or embarrassing, but it wasn’t when I was in school. I envy people who grew up enjoying that stuff!

  8. I ran across the country when I was 21 so I could remember a story to tell my grand kids if I get to be 91.

  9. @Rudy Same for me. I was anchored to the idea that athelics were not for me. I was sadly mistaken. But, better a late bloomer than not at all.

  10. As the P.E. teacher I was keenly aware that it was necessary to find something that each student could find fun and interesting to take into adulthood to keep them active. Don’t think I was always successful but I gave it a good go.

    One entire class of ornery 9th graders hated PE until I took them into modern dance. They loved it which made us all very happy.

    It is too bad that poor experiences put us off activities that we could be enjoying. Guess that happens with all subjects. History, math, etc.

    But like you say Debra, better a late bloomer than not at all. Maybe there is a lesson here for us all to be open to things we think we are not good at or don’t like.

    1. “It is too bad that poor experiences put us off activities that we could be enjoying. Guess that happens with all subjects. History, math, etc.”

      Truer words…I teach English and it’s a struggle to find something to help all students engage in learning as something fun, not just drudgery that gets them to college or at least HS graduation.

      My PE experience was the same until junior year of HS when we had “Challenge” wherein we climbed rocks, hiked, learned to tie knots and use teamwork to built huts or cross chasms. My PE teacher took us on an Outward Bound expedition that Spring and my always-there-but-never-full-fruited love of the outdoors blossomed into an eternal flower of fitness and fresh air. Thank goodness for Mr. Rushnak!

  11. Read your book after the owner of Rivendell bicycles basically put it in my hands. Great stuff. I’ve been lifting, running, and cycling since I was 12. Mostly lifting because I was the 98 pound weakling in a rough and tumble Texas town. One of the things that’s happening now that I am soon to be 53 is the huge gap in fitness, and “visual age” between my peers and myself. Holy crapola. Also my verbal and mental quickness is much better than my peer group. Research is research and I love reading this stuff, but real hard evidence is right in front of my face everyday. I can’t bring myself to eat your four whole eggs at breakfast yet. Still prefer egg whites in oatmeal…. I” wait to see how you do over the next decade…

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